The present novel concept broadly relates to the art of fluid suspension members and, more particularly, to a spacer having a self-indexing feature for use in forming a self-aligning air spring assembly.
The subject self-indexing spacer finds particular application in association with the use of air springs in forming a suspension system of a vehicle and will be discussed herein with particular reference thereto. However, it is to be specifically understood that the subject novel concept is capable of broad use and, as such, is equally applicable for use in other suitable environments, such as machinery mount applications, for example. Additionally, it will likewise be understood that the subject self-indexing spacer is also suitable for use in association with fluid suspension members of various types and kinds, in addition to those specifically discussed herein, without departing from the principles of the present novel concept.
Air springs and other such fluid suspension members are well known and commonly used in a broad range of applications. It is well understood that such applications have or establish design criteria, such as load capacity, spring rate, range of motion and/or size constraints, to which a properly selected and/or designed air spring will conform. Of course, an air spring having a diameter or other maximum cross-sectional dimension that is greater than that permitted by an established mounting envelope or other size limitation would likely be judged to be unsuitable for use in such an application. However, other situations arise in which an otherwise entirely suitable air spring will have a shorter nominal height than that called for by a particular application. Under these circumstances, it is often undesirable to use this otherwise suitable air spring in the application, as such use may undesirably limit a characteristic or function of the air spring, such as limiting travel, for example. Furthermore, over-extension of an air spring can, under most circumstances, be detrimental to one or more components thereof and, as such, is preferably avoided.
To overcome such concerns, spacers have been developed that make up the difference between the nominal height of the air spring and the design height specified in or otherwise established by the particular application or use. One example of such a spacer is disclosed in U.S. Pat. No. 6,250,613 (the '613 patent), which is incorporated herein by reference in its entirety. Basically, these spacers act to fill in the gap between an end member of the air spring and the associated vehicle component or other mounting surface.
One disadvantage of using such spacers, however, is that the difficulty associated with installing the air spring is increased. This is largely due to the added challenge of aligning the spacer with the various mounting holes of the air spring and the associated suspension component and maintaining this alignment during the installation process. Where such an alignment is not maintained, the fastening members will not engage the mounting holes until the components have been realigned. This can be particularly problematic where multiple spacers are used and are being stacked together to make up the difference between the air spring height and the design height of the vehicle suspension.
In other arrangements, the air spring will include a single fastener that projects from the end member or is received into the end member to mount the air spring. In these situations, the challenge of maintaining alignment of the spacers is reduced. However, another issue is raised in such situations which is related to the transmission of the associated vehicle loads through the one or more spacers. More specifically, spacers, such as those shown in the '613 patent, are capable of supporting the entire load on the associated air spring and transmitting the load to the associated suspension component. As shown in the '613 patent, however, such spacers can include a plurality of cored areas or other features that may be advantageous for manufacturing or other purposes. These cored areas are separated by a plurality of inner walls, often referred to as center tubes and/or ribs by those of skill in the art, that are formed inside the outer peripheral wall of the spacer.
Where the end member of an air spring is formed from a polymeric material, which is a common practice, similar cored areas and walls may be formed on the end member inwardly of the peripheral wall thereof. In such arrangements, it is desirable to have the inside walls of the end member and the inner walls of the spacer in substantial alignment with one another to transmit the associated loads through to the suspension component. Though more difficult to initially align, this is less of an issue where two or more fasteners are used because the fasteners will limit the rotation of the spacer relative to the end member. However, since many air springs are secured using a single fastening member that centrally extends from or engages the end member, it is more of a challenge to position the spacer and end member such that the inside walls thereof are properly aligned. Furthermore, the level of difficulty is again increased where multiple spacers are being used and secured between the end member and the vehicle suspension component with a single fastener.